[NET]: Fix heavy stack usage in seq_file output routines.

Plan C: we can follow the Al Viro's proposal about %n like in this patch.
The same applies to udp, fib (the /proc/net/route file), rt_cache and 
sctp debug. This is minus ~150-200 bytes for each.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 7 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b053ac795275..1f535e315188 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1619,7 +1619,8 @@ void udp_proc_unregister(struct net *net, struct udp_seq_afinfo *afinfo)
 }
 
 /* ------------------------------------------------------------------------ */
-static void udp4_format_sock(struct sock *sp, char *tmpbuf, int bucket)
+static void udp4_format_sock(struct sock *sp, struct seq_file *f,
+                int bucket, int *len)
 {
         struct inet_sock *inet = inet_sk(sp);
         __be32 dest = inet->daddr;
@@ -1627,13 +1628,13 @@ static void udp4_format_sock(struct sock *sp, char *tmpbuf, int bucket)
         __u16 destp       = ntohs(inet->dport);
         __u16 srcp        = ntohs(inet->sport);
 
-        sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
-                " %02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %p",
+        seq_printf(f, "%4d: %08X:%04X %08X:%04X"
+                " %02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %p%n",
                 bucket, src, srcp, dest, destp, sp->sk_state,
                 atomic_read(&sp->sk_wmem_alloc),
                 atomic_read(&sp->sk_rmem_alloc),
                 0, 0L, 0, sock_i_uid(sp), 0, sock_i_ino(sp),
-                atomic_read(&sp->sk_refcnt), sp);
+                atomic_read(&sp->sk_refcnt), sp, len);
 }
 
 int udp4_seq_show(struct seq_file *seq, void *v)
@@ -1644,11 +1645,11 @@ int udp4_seq_show(struct seq_file *seq, void *v)
                            "rx_queue tr tm->when retrnsmt   uid  timeout "
                            "inode");
         else {
-                char tmpbuf[129];
                 struct udp_iter_state *state = seq->private;
+                int len;
 
-                udp4_format_sock(v, tmpbuf, state->bucket);
-                seq_printf(seq, "%-127s\n", tmpbuf);
+                udp4_format_sock(v, seq, state->bucket, &len);
+                seq_printf(seq, "%*s\n", 127 - len ,"");
         }
         return 0;
 }